Add the frozen berries to a pan on a medium heat. Cook until soft enough to mash with a fork and the juices have released. This will take around 5 minutes.
Remove from the heat and add the chia seeds, lemon juice and honey. Stir well and allow to cool while you make the banana bread.
Making The Banana Bread
Preheat oven at fan 160 and line a 9×5-inch loaf pan with parchment paper.
Make oat flour: Blend oats in a blender or food processor until fine.
Mash the bananas in a large bowl. Whisk in the eggs, syrup, yogurt, and oil until smooth.
Add the oat flour, baking soda, baking powder, cinnamon, and salt. Stir until combined.
Pour half the batter into prepared loaf pan. Spoon in 3-4 tbsp of the chia jam and spread evenly. Pour the rest of the banana bread mixture on top before adding 1-2 tbsp of the chia jam on top... swirl the jam through the mixture using the end of a spoon or skewer.
Bake for 45–55 minutes, or until a toothpick comes out clean.